Biol Reprod Track the topics, authors and articles important to you
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

BOR - Papers in Press, published online ahead of print October 4, 2002.
Biol Reprod 2002, 10.1095/biolreprod.102.006700
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
67/6/1804    most recent
biolreprod.102.006700v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Rockwell, L. C.
Right arrow Articles by Koos, R. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Rockwell, L. C.
Right arrow Articles by Koos, R. D.
Agricola
Right arrow Articles by Rockwell, L. C.
Right arrow Articles by Koos, R. D.
Biology of Reproduction 67, 1804-1810 (2002)
DOI: 10.1095/biolreprod.102.006700 © 2002 Society for the Study of Reproduction, Inc.

Female Reproductive Tract

Inhibition of Vascular Endothelial Growth Factor/Vascular Permeability Factor Action Blocks Estrogen-Induced Uterine Edema and Implantation in Rodents1

L. Christie Rockwell2,a, Suresh Pillaia, C. Erik Olsona, and Robert D. Koosa

a Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Estrogen induces a rapid increase in microvascular permeability in the rodent uterus, leading to stromal edema and a marked increase in uterine wet weight. This edema is believed to create an environment optimal for the growth and remodeling of the endometrium in preparation for implantation and pregnancy. Increased endometrial microvascular permeability also occurs in conjunction with implantation. Estrogen-induced uterine edema is immediately preceded by an increase in the expression of vascular endothelial growth factor (VEGF), a potent stimulator of microvascular permeability. The objective of this study was to determine to what degree immunoneutralization of VEGF would interfere with a) estradiol-induced uterine edema and b) pregnancy. In the first set of experiments, immature female rats were injected with either VEGF antiserum or normal rabbit serum (NRS) prior to 17ß-estradiol treatment. Rats treated with estradiol alone showed a 57% increase in uterine wet weight at 6 h compared with controls. Injection of 200 or 300 µl of VEGF antiserum reduced the response to only 20% and 10% above controls, respectively. In the second set of experiments, young adult female mice were treated with 100 µl of either VEGF antiserum or NRS at 1200 h on the fourth day after mating. NRS-treated mice had normal pregnancies. VEGF antiserum, however, completely blocked pregnancy. When VEGF antiserum-treated females were examined on Day 5 for the presence of implantation sites, none were found. These results show that a) VEGF is the major mediator of estrogen-induced increase in uterine vascular permeability and b) VEGF-induced edema is absolutely essential for implantation to take place.

estradiol, female reproductive tract, implantation, pregnancy, uterus


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
One of the earliest events to occur in the rodent uterus after treatment with estrogen is a marked increase in microvascular permeability [1, 2]. This, in combination with an estrogen-induced increase in blood flow [3], leads to edema in the endometrial stroma [4]. These changes closely resemble those that occur in response to endogenous estrogen during proestrus in the normal adult rodent [5]. Edema is also a characteristic of the human endometrial stroma during both the midproliferative and midsecretory phases of the menstrual cycle [6–8], periods that correspond to increases in estrogen production by first the developing follicle and then the corpus luteum. Furthermore, exogenous estrogen induces massive stromal edema in the human endometrium [9], as it does in the rat and mouse. In the rat and mouse, increases in endometrial microvascular permeability and edema also occur in conjunction with implantation; this presumably involves the brief spike in estrogen that triggers the implantation process [10, 11]. This phenomenon makes it possible to readily visualize implantation sites with the naked eye following i.v. injection of blue dyes, such as Evans Blue, that bind to serum proteins [11]. Marked edema also occurs peripheral to the implanting blastocyst in primates [12].

The function of increased microvascular permeability and edema in the uterus before and during implantation is not well understood. In general, increased permeability is thought to play essential roles in the induction and direction of tissue growth and remodeling wherever it occurs [13]. Thus, it may first of all be a basic requirement for the rapid growth and differentiation of the endometrium in preparation for implantation and pregnancy. In addition, it appears to play a specific and causal role in the decidualization reaction [11, 14], which it immediately precedes [15]. In this regard, edema serves to clasp the blastocyst in the uterine lumen [16], bringing it in intimate association with the epithelium. Edema has also been proposed to cause differential uterine elongation and growth (an increase in uterine length at implantation sites and a decrease between sites), contributing to even spacing between blastocysts [17]. Finally, increased permeability and edema would facilitate the angiogenesis associated with the maternal component of placenta formation [13]. Identification of the mediators of increased permeability in the uterus, therefore, has great significance for understanding the physiological role of uterine vascular permeability and edema in the development of a receptive endometrium and in the implantation process.

The most potent inducer of increased microvascular permeability yet identified is vascular endothelial growth factor/vascular permeability factor (VEGF/VPF, hereafter referred to as VEGF) [18, 19]. Three major forms of VEGF (120, 164, and 188 aa in length in the rat) arise from alternative splicing of a single gene [20]; all are capable of stimulating microvascular permeability [21]. VEGF is also a specific endothelial cell mitogen that appears to play a central role in angiogenesis [20, 22]. Its angiogenic action may, in part, result from the enhancement of permeability, which invariably precedes new blood vessel growth [13]. We have previously demonstrated that steady-state levels of the mRNA for VEGF increase rapidly in the uterus following estrogen treatment [23]. VEGF and the VEGF receptors Flt-1 and Flk-1 are also expressed in the human endometrium at all stages of the menstrual cycle [24–26] and levels of VEGF mRNA tend to be higher in the secretory phase [25], the period of maximum microvascular permeability and greatest edema [6]. It is also likely that VEGF is responsible for the edema associated with implantation based on localization of VEGF, as well as the VEGF receptors, immediately around the implanting blastocyst in several species [27–31].

The close temporal and spatial correlation between VEGF expression and increased vascular permeability in the uterus suggests that VEGF is the factor responsible for this phenomenon. Other indirect support for this relationship comes from the similarity in the effects of VEGF on blood vessels observed in other systems [32] and that seen in the uterus in response to estrogen and at implantation sites, namely the formation of intercellular gaps and an increase in the incidence of fenestrae (from 3% to 78%) [33–36]. Additional indirect support for VEGF's role in these events comes from the observations that prior administration of actinomycin D blocks both estrogen-induced VEGF expression [23] and uterine edema [37].

It nevertheless remains to be definitively demonstrated that VEGF is the mediator of these events. The i.v. administration of a VEGF monoclonal antibody has been shown to acutely reduce vascular permeability induced by tumor implants in nude mice [38]. In two other studies in mice, polyclonal antisera against hVEGF have been shown to inhibit pathological processes in which VEGF was postulated to play a role: granulomatous inflammation [39] and postoperative adhesion formation [40]. We adopted this approach, therefore, to determine a) whether VEGF is the factor responsible for the increase in microvascular permeability in the uterus after treatment with estrogen and at the time of implantation, and, if so, b) to what degree the latter process is dependent on this increase in permeability.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Animal studies were conducted in accordance with the NIH Guide for the Care and Use of Laboratory Animals and approved by the IACUC of the University of Maryland School of Medicine.

Acute Response to Exogenous Estrogen in Immature Rats

For each experiment, animals were weighed and randomly distributed into treatment groups. Immature, 23-day-old Sprague Dawley rats (Crl:CD[SD] BR strain; Charles River, Wilmington, MA) were anesthetized with ketamine (75 mg/kg)/acepromazine (2.5 mg/kg) to facilitate the tail vein injections. Trial studies demonstrated that anesthesia did not prevent the estrogen-induced increase in uterine wet weight at 6 h (data not shown). A rabbit antiserum made against recombinant human VEGF (provided by Dr. Daniel Connolly, Monsanto, St. Louis, MO; [41]) or normal rabbit serum (NRS, control) was injected (100–300 µl) into a tail vein using a 30-gauge needle. Animals were then injected (i.p.) with 17ß-estradiol (5 µg/100 g body weight; Sigma, St. Louis, MO) or vehicle. They were then placed in a warm cage and killed by cervical dislocation 6 h after injection. The reproductive tract was quickly dissected from each animal and placed on moist paper. The uteri were isolated by uniformly cutting at the cervical and tubal junctions and then trimming away the mesometrium. They were then weighed on a Mettler AE50 microbalance. Immediately after weighing, uteri were fixed in 10% buffered formalin. They were then embedded in paraffin, sectioned (8 µm), and stained with either hematoxylin-eosin or picric acid-methyl blue. Sections were examined and photographed using an Olympus (Lake Success, NY) BX40 microscope.

Mouse Pregnancy

Experiments on the effects of the VEGF antiserum on implantation were carried out in mice rather than rats. The process of implantation is highly similar in these two species [15, 16] and has been studied most extensively in the former. Eight- to 10-wk-old, virgin female mice (FVB strain; Charles River) were cohoused with adult males and checked daily for the presence of a vaginal plug (Day 1 of pregnancy). At 1200 h on Day 4 of pregnancy, one group of females (controls) received 100 µl of NRS (i.v.), while the other group received 100 µl of VEGF antiserum. This time was chosen because implantation, as indicted by the blue-dye test, normally begins late on Day 4 in the mouse [15].

In the first of two experiments, the females (n = 7 control; n = 8 VEGF antiserum-treated) were observed and weighed daily until the normal time of parturition, 19 days (or for at least 1 wk longer if no pups were produced at the expected time). The number of pups born and the length of gestation were recorded. In the second experiment, the blue-dye response on Day 5 of pregnancy was tested. In the latter experiment, all animals were injected (i.v.) with 100 µl of 5% Evans Blue Dye in PBS under light anesthesia 24 h following the injection of 100 µl of antiserum (n = 3) or NRS (n = 3). Fifteen minutes after the injection of dye, the animals were killed by cervical dislocation. An abdominal incision was made to expose the ovaries and uterus and the reproductive tract was carefully dissected free and photographed. One uterine horn from each animal was processed for histology, serially sectioned (8 µm), and stained with picric acid-methyl blue. These sections were examined for the presence of blastocysts and implantation sites.

Statistical Analysis

Uterine weights and litter sizes were compared by analysis of variance followed by appropriate post hoc tests using StatView (Abacus Concepts, Berkeley, CA).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
A single injection of estrogen rapidly induces uterine edema in immature rats. The effect of the VEGF antiserum on this response was first examined. In all experiments, immature rats treated with estradiol and NRS showed an average 57% increase in uterine wet weight at 6 h compared with unstimulated controls (Fig. 1). This increase is similar to that reported in classic studies of estrogen-induced uterine edema by Astwood [4]. Injection of 100 µl of VEGF antiserum had no significant effect on the increase in wet weight (Fig. 1, left panel), although the result was variable from one trial to another, with a 38% reduction in weight occurring in one of the three trials. In the two groups treated with 200 µl or 300 µl of antiserum, however, the increases in wet weight were only 20% and 9.8% above the control groups, respectively (Fig. 1, center and right panels). These uterine weight values were not statistically different from those in the respective control groups (P > 0.2 and 0.4, respectively) but were significantly less than the groups treated with estradiol and NRS (P < 0.01 in both cases).



View larger version (12K):
[in this window]
[in a new window]
  		FIG. 1. The effect of VEGF antiserum on the 17ß-estradiol-induced increase in uterine wet weight in immature rats. Uterine weights (mean ± SEM) are normalized per gram body weight. Left panel: 100 µl antiserum or NRS; center panel: 200 µl antiserum or NRS; right panel: 300 µl antiserum or NRS. The number of rats in each group is indicated at the base of each bar. *P < 0.01 versus control group; **P = 0.01 versus estradiol-only group

Cross sections of the uteri from the three treatment groups are shown in Figure 2. The endometrial stromal cells of control uteri were compact, with closely spaced nuclei and little or no intercellular gaps (Fig. 2, A and B). As expected, estradiol induced a large decrease in cellular density and a large increase in intercellular space, indicative of fluid accumulation, throughout the endometrial stroma except in the immediate mesometrial area (Fig. 2, C and D). In marked contrast with this, uteri from animals treated with VEGF antiserum (200 or 300 µl) before estrogen treatment were indistinguishable from control animals (Fig. 2, E and F).



View larger version (98K):
[in this window]
[in a new window]
  		FIG. 2. Cross-sections of a representative uterine horn from each of the three treatent groups. A, B) Control group; C, D) estradiol plus NRS group; E, F) estradiol plus VEGF antiserum (300 µl) group. Original magnifications x100 (A, C, E) and x400 (B, E, F). In each case, the antimesometrial side of the uterus is to the left

The effect of the antiserum to VEGF, given on the fourth day after mating (the normal day of implantation), on pregnancy was then evaluated. All control animals (i.e., NRS treated) in which a vaginal plug had been observed (n = 7) delivered pups. The length of gestation averaged 19 days, and the average litter size (±SEM) was 9.3 ± 0.29. In contrast with this and although a vaginal plug had been observed in all animals prior to treatment, 100% of females treated with VEGF antiserum (n = 8) failed to deliver any pups. There was also no significant weight gain in these females following mating (data not shown).

The complete blockade of pregnancy and the lack of any sign of normal weight gain suggested that the VEGF antiserum had probably blocked implantation rather than some later stage of gestation. This was confirmed when the blue-dye response was tested. Figure 3, A–C, shows the blue-dye response in control (i.e., pregnant) animals (n = 3). The blue bands, which mark the implantation sites, were distinct, with 10–13 implantation sites per animal. There was also noticeable swelling at each site, giving the uterine horns the normal beads-on-a-string appearance. In the three VEGF antiserum-treated uteri, by contrast, no distinct implantation sites were visible. Some diffuse, light bluish areas could be distinguished in two of these uteri, but they were much less distinct than the well-defined dark blue implantation sites in the control uteri (Fig. 3, D–F).



View larger version (27K):
[in this window]
[in a new window]
  		FIG. 3. The effect of VEGF antiserum on implantation in mice. The presence (arrows) or absence of implantation sites was visualized on Day 5 of pregnancy by the injection of Evans Blue. Females were injected on Day 4 of pregnancy with either NRS (A–C) or VEGF antiserum (D–F)

Histological analysis was carried out on the same uteri. The implantation sites from control animals had the normal characteristics for Day 5 of pregnancy: hypertrophied decidual cells, elongated blastocysts, clusters of apoptotic nuclei in the antimesometrial primary decidual zone, and a disrupted epithelium (Fig. 4, A and B). In contrast, there was no sign of implantation in the antiserum-treated animals. Few blastocysts were located, but those that were present were still small and often degenerating. They were usually present at the antimesometrial pole, the correct location for normal initial attachment. The lumen was open, however, and there was no indication of blastocyst invasion, i.e., the uterine epithelium and basement membrane were intact (Fig. 4, C and D). There was also no sign of stromal decidualization adjacent to these blastocysts.



View larger version (79K):
[in this window]
[in a new window]
  		FIG. 4. Histologic sections of representative uteri from the groups of animals treated with NRS (A, B; * marks the ectoplacental cone) or VEGF antiserum (C, D; arrows indicate the basement membrane of the uterine epithelium)


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The first significant finding in this study is that VEGF is the principle mediator of the increase in vascular permeability that takes place in the uterus in response to estrogen. The identity of the factor responsible for this event has been sought for more than 50 years. While absolutely essential for this effect, the VEGF-induced increase in permeability would not in itself be sufficient to induce a major increase in uterine edema. That would only occur if there were a simultaneous increase in blood flow as well [42, 43]. It is well established, of course, that estrogen does induce a rapid increase in uterine blood flow [3, 44]. This increase in blood flow may explain why the estrogen plus VEGF antiserum-treated rat uteri tended to be slightly larger than the control uteri (although the difference was not statistically significant) and may also explain the very faint and diffuse blue staining of the uteri of mated, anti-VEGF-treated mice even though no implantation occurred. Increased uterine blood flow would both increase intravascular blood volume (2.5- to 2.7-fold) [45, 46] and raise capillary hydrostatic pressure. The latter would be predicted to increase net filtration without any change in permeability, perhaps resulting in a modest increase in steady-state interstitial fluid volume. The estrogen-induced increase in uterine blood flow is probably mediated primarily by nitric oxide (NO) because it is blocked by inhibitors of NO synthesis [47, 48]. It is not surprising, therefore, that such inhibitors have also been reported to block estrogen-induced uterine edema [49]. It is also possible that factors other than VEGF may be responsible for a small increase in permeability. Some residual permeability-inducing activity, similar to the amount seen here, remained in rat 9L glioma cell-conditioned medium after VEGF was removed by immunoprecipitation [50].

The response to the three different doses of antibody—no significant effect with 100 µl and nearly complete inhibition with 200 or 300 µl—suggests that the lower dose was near the threshold necessary to achieve high enough levels within the uterus to block VEGF's effect. This is further suggested by the fact that the lower dose did result in substantial inhibition (38%) in one of three trials.

The second major finding of this study is that VEGF action is necessary for the increase in microvascular permeability that follows the nidatory estrogen signal and that, in the absence of VEGF-induced edema, implantation fails completely. The uteri from VEGF antiserum-treated animals showed no signs of closure of the lumen, breakdown of the luminal epithelium, or decidualization. Unable to implant, the blastocysts apparently could not develop further and showed signs of deterioration. Increased permeability is the first definitive event in decidualization and as such has been suggested to be necessary for that complex reaction to take place [11, 14, 51, 52]. The edema associated with implantation is initially generalized, causing closure of the uterine lumen throughout the length of the horn, but then becomes localized at the sight of blastocyst-uterine contact [53, 54]. This suggests that the blastocyst itself may further enhance VEGF production specifically at the implantation site.

The demonstration that an antiserum to VEGF inhibits the rapid increase in uterine edema that follows estrogen treatment strongly suggests that this is the mechanism by which it blocks implantation. Results similar to ours on the effect of an antibody to VEGF on implantation were recently reported in rats [55]. In that study, however, treatment was initiated on Day 3 of pregnancy, well before the nidatory estradiol peak. In that case, it is possible that ovarian steroidogenesis was altered. It has been demonstrated that inhibition of VEGF action can inhibit corpus luteum formation in rats and marmosets [56–58]. It has also been shown that administration of an anti-VEGF antibody to marmosets during the midluteal phase can significantly lower progesterone production [59]. We cannot, at this time, completely rule out the possibility that inhibition of VEGF action also affected steroid synthesis in our study, but in both the rat and mouse, progesterone levels are already maximal by the morning of Day 4 of pregnancy and the nidatory estradiol rise has already occurred [10, 60, 61]. Coming in the wake of the normal preovulatory rise in estradiol, these events should be sufficient to fully sensitize the uterus for implantation [62]. Furthermore, only brief exposure to low levels of estrogen is needed to trigger implantation [63]. It seems unlikely, therefore, that VEGF antiserum treatment in the middle of Day 4 could shut down progesterone and estradiol synthesis so rapidly and so completely that it would prevent any sign of implantation. Nevertheless, additional studies in which the effects of immunoneutralization of VEGF on implantation in ovariectomized animals given exogenous progesterone and estrogen to induce implantation will be needed to completely rule out this possibility.

There are several possible reasons why edema might be essential for implantation to take place. As discussed previously, one likely role is to occlude the lumen, thereby clasping the blastocysts and bringing them into intimate contact with the epithelial cells lining the uterine lumen. This may trigger the breakdown of the latter, placing the blastocyst into direct contact with the endometrial stroma, where it further enhances local microvascular permeability and the decidualization process. Second, increased microvascular permeability is probably required for the rapid growth and remodeling of the endometrium at implantation sites. Transient edema, induced by ligation of a uterine vein, has in fact been shown to markedly stimulate uterine growth [64]. Edema infuses the extravascular compartment with plasma proteins, such as plasminogen, which participate in the breakdown of the existing extracellular matrix, and fibrinogen, which, after conversion to fibrin, forms a provisional matrix favorable to cell migration, proliferation, and differentiation. Experimental evidence shows that such a sequence does occur in the endometrium in association with estrogen-induced edema. In rats, the well-organized endometrial network of collagen fibers almost completely disappears within 4 h of estrogen treatment, the time when maximum edema is reached [65]. There is also widespread extravascular fibrin deposition in the human endometrium after estrogen treatment [25]. VEGF probably further enhances matrix remodeling by stimulating the production of proteases, such as plasminogen activator and collagenase, by stromal capillary endothelial cells [66, 67]. Increased permeability would also facilitate the extravasation of other blood-borne elements, such as growth factors (e.g., insulin-like growth factors), platelets, and leukocytes, further optimizing conditions for endometrial remodeling. Furthermore, it may also enhance the efficiency of delivery of oxygen and basic nutrients to areas of heightened cell activity by creating a more direct circulatory pathway—from capillaries through the interstitial spaces to the lumen—thereby greatly reducing normal diffusional distances. Finally, the increase in permeability may serve as a positive feedback mechanism in estrogen action. When levels of estrogen are low, uterine capillaries are relatively impermeable to estradiol, which circulates bound to serum proteins [68]. By facilitating the passage of these proteins to the interstitium, increased permeability would enhance estrogen delivery as well.

In summary, these studies support the propositions that a) VEGF is the major mediator of the estrogen-induced increase in uterine vascular permeability and edema and b) VEGF-induced edema is absolutely essential for implantation to take place. This opens new avenues of investigation to better define the physiological functions of both VEGF and the edema it induces in the establishment of pregnancy.


   ACKNOWLEDGMENTS
 
The authors would like to thank Dr. Daniel Connelly for the generous gift of the VEGF antiserum used in these studies. We also thank Dr. Anne Hirshfield and Ms. Andrea DeSanti for their assistance with the preparation of the rat histologic sections, Ms. Donna Suresh for assistance with the preparation of the mouse histologic sections, Meredith Rocca for additional technical assistance, and Dr. Robert Bloch for the donation of normal rabbit serum.


   FOOTNOTES
 
1 This research was supported by NIH/NCI grant CA45055, with a supplement from the Office of Research on Women's Health, Agreement U54 HD36207 (Specialized Cooperative Center in Reproduction Research at the University of Maryland School of Medicine as part of the NICHD's Specialized Cooperative Centers Program in Reproduction Research), and NIH/NICHD Institutional Training Grant HD07170. Preliminary reports of this work were presented at the 31st annual meeting of the Society for the Study of Reproduction, Portland, OR, 1998, and at the 34th annual meeting of the Society for the Study of Reproduction, Ottawa, Canada, 2001. Back

2 Correspondence and current address: L. Christie Rockwell, Department of Anthropology, Temple University, 1115 W. Berks Street, Philadelphia, PA 19122. FAX: 215 204 1410; lrockwel{at}temple.edu Back

Received: 9 May 2002.

First decision: 5 June 2002.

Accepted: 1 July 2002.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Hechter O, Krohn L, Harris J. The effect of estrogen on the permeability of the uterine capillaries. Endocrinology 1941 29:386-392
  2. Martin L, Finn CA. Interactions of oestradiol and progestins in the mouse uterus. J Endocrinol 1970 48:109-115[Abstract/Free Full Text]
  3. Phaily S, Senior J. Modification of oestrogen-induced uterine hyperaemia by drugs in the ovariectomized rat. J Reprod Fertil 1978 53:91-97[Abstract/Free Full Text]
  4. Astwood EB. A six-h assay for the quantitative determination of estrogen. Endocrinology 1938 23:25-31
  5. Astwood EB. Changes in the weight and water content of the uterus of the normal adult rat. Am J Physiol 1939 126:162-170[Free Full Text]
  6. Noyes RW, Hertig AT, Rock J. Dating the endometrial biopsy. Fertil Steril 1950 1:3-25
  7. Johannisson E, Parker RA, Landgren B, Diczfalusy E. Morphometric analysis of the human endometrium in relation to peripheral hormone levels. Fertil Steril 1982 38:564-571[Medline]
  8. Jeziorska M, Salamonsen LA, Woolley DE. Mast cell and eosinophil distribution and activation in human endometrium throughout the menstrual cycle. Biol Reprod 1995 53:312-320[Abstract]
  9. Klebe U, Moltz L, Pickartz H. Effects of cyproterone acetate and ethinylestradiol on endometrial histology. Arch Gynecol 1983 234:113-120[Medline]
  10. McCormack JT, Greenwald GS. Evidence for a preimplantation rise in oestradiol-17beta levels on day 4 of pregnancy in the mouse. J Reprod Fertil 1974 41:297-301[Abstract/Free Full Text]
  11. Psychoyos A. Endocrine control of egg implantation. In: Greep RO, Astwood EG, Geiger SR (eds.), Handbook of Physiology, section 7, vol. II, part 2. Washington, DC: American Physiological Society; 1973: 187–215
  12. Enders AC, Welsh AO, Schlafke S. Implantation in the Rhesus monkey: endometrial responses. Am J Anat 1985 173:147-169[CrossRef]
  13. Dvorak HF, Brown LF, Detmar M, Dvorak AM. Vascular permeability factor/vascular endothelial growth factor, microvascular hyperpermeability, and angiogenesis. Am J Pathol 1995 146:1029-1039[Abstract]
  14. Hamilton GS, Kennedy TG. Uterine extracellular fluid volume and blood flow after artificial uterine stimulation to rats differentially sensitized for the decidual cell reaction. Biol Reprod 1993 48:910-915[Abstract]
  15. Finn CA, McLaren A. A study of the early stages of implantation in mice. J Reprod Fertil 1967 13:259-267[Abstract/Free Full Text]
  16. Enders AC, Schlafke S. A morphological analysis of the early implantation stages in the rat. Am J Anat 1967 120:185-226[CrossRef]
  17. Rogers PAW, Murphy CR, Gannon BJ. Changes in the spatial organization of the uterine vasculature during implantation in the rat. J Reprod Fertil 1982 65:211-214[Abstract/Free Full Text]
  18. Connolly DT, Olander JV, Heuvelman D, Nelson R, Minsell R, Siegel N, Haymore BL, Leimgruber R, Feder J. Human vascular permeability factor: isolation from U937 cells. J Biol Chem 1989 264:20017-20024[Abstract/Free Full Text]
  19. Senger DR, Van De Water L, Brown LF, Nagy JA, Yeo K-T, Yeo T-K, Berse B, Jackman RW, Dvorak AM, Dvorak HF. Vascular permeability factor (VPF, VEGF) in tumor biology. Cancer Metastasis Rev 1993 12:303-324[CrossRef][Medline]
  20. Ferrara N, Houck K, Jakeman L, Leung DW. Molecular and biological properties of the vascular endothelial growth factor family of proteins. Endocr Rev 1992 13:18-32[CrossRef][Medline]
  21. Houck KA, Ferrara N, Winer J, Cachianes G, Li B, Leung DW. The vascular endothelial growth factor family: identification of a fourth molecular species and characterization of alternative splicing of RNA. Mol Endocrinol 1991 5:1806-1814[CrossRef][Medline]
  22. Ferrara N, Davis-Smyth T. The biology of vascular endothelial growth factor. Endocr Rev 1997 18:4-25[Abstract/Free Full Text]
  23. Cullinan-Bove K, Koos RD. Vascular endothelial growth factor/vascular permeability factor expression in the rat uterus: rapid stimulation by estrogen correlates with estrogen-induced increases in uterine capillary permeability and growth. Endocrinology 1993 133:829-837[Abstract]
  24. Charnock-Jones DS, Sharkey AM, Rajput-Williams J, Burch D, Schofield JP, Fountain SA, Boocock CA, Smith SK. Identification and localization of alternately spliced mRNAs for vascular endothelial growth factor in human uterus and estrogen regulation in endometrial carcinoma cell lines. Biol Reprod 1993 48:1120-1128[Abstract]
  25. Torry DS, Holt VJ, Keenan JA, Harris G, Caudle MR, Torry RJ. Vascular endothelial growth factor expression in cycling human endometrium. Fertil Steril 1996 66:72-80[Medline]
  26. Meduri G, Bausero P, Perrot-Applanat M. Expression of vascular endothelial growth factor receptors in the human endometrium: modulation during the menstrual cycle. Biol Reprod 2000 62:439-447[Abstract/Free Full Text]
  27. Jakeman LB, Armanini M, Phillips HS, Ferrara N. Developmental expression of binding sites and messenger ribonucleic acid for vascular endothelial growth factor suggests a role for this protein in vasculogenesis and angiogenesis. Endocrinology 1993 133:848-859[Abstract]
  28. Chakraborty I, Das SK, Dey SK. Differential expression of vascular endothelial growth factor and its receptor mRNAs in the mouse uterus around the time of implantation. J Endocrinol 1995 147:339-352[Abstract/Free Full Text]
  29. Yi XJ, Jiang HY, Lee KK, O WS, Tang PL, Chow PH. Expression of vascular endothelial growth factor (VEGF) and its receptors during embryonic implantation in the golden hamster (Mesocricetus auratus). Cell Tissue Res 1999 296:339-349[CrossRef][Medline]
  30. Das SK, Chakraborty I, Wang J, Dey SK, Hoffman LH. Expression of vascular endothelial growth factor (VEGF) and VEGF-receptor messenger ribonucleic acids in the peri-implantation rabbit uterus. Biol Reprod 1997 56:1390-1399[Abstract]
  31. Halder JB, Zhao X, Soker S, Paria BC, Klagsbrun M, Das SK, Dey SK. Differential expression of VEGF isoforms and VEGF(164)-specific receptor neuropilin-1 in the mouse uterus suggests a role for VEGF(164) in vascular permeability and angiogenesis during implantation. Genesis 2000 26:213-224[CrossRef][Medline]
  32. Roberts WG, Palade GE. Increased microvascular permeability and endothelial fenestration induced by vascular endothelial growth factor. J Cell Sci 1995 108:2369-2379[Abstract]
  33. Friederici HHR. The early response of uterine capillaries to estrogen stimulation. An electron microscopic study. Lab Invest 1967 17:322-333[Medline]
  34. Ham KN, Hurley JV, Lopata A, Ryan GB. A combined isotopic and electron microscopic study of the response of the rat uterus to exogenous oestradiol. J Endocrinol 1970 46:71-81[Abstract/Free Full Text]
  35. Martin L, Hallowes RC, Finn CA, West DG. Involvement of the uterine blood vessels in the refractory state of the uterine stroma which follows oestrogen stimulation in progesterone-treated mice. J Endocrinol 1973 56:309-314[Abstract/Free Full Text]
  36. Abrahamsohn P, Lundkvist O, Nilsson O. Ultrastructure of the endometrial blood vessels during implantation of the rat blastocyst. Cell Tissue Res 1983 229:269-280[Medline]
  37. Ui H, Mueller GC. The role of RNA synthesis in early estrogen action. Proc Natl Acad Sci U S A 1963 50:256-260[Free Full Text]
  38. Yuan F, Chen Y, Dellian M, Safabakhsh N, Ferrara N, Jain RK. Time-dependent vascular regression and permeability changes in established xenografts induced by an anti-vascular endothelial growth factor/vascular permeability factor antibody. Proc Natl Acad Sci U S A 1996 93:14765-14766[Abstract/Free Full Text]
  39. Appleton I, Brown NJ, Willis D, Colville-Nash PR, Alam C, Brown JR, Willoughby DA. The role of vascular endothelial growth factor in a murine chronic granulomatous tissue air pouch model of angiogenesis. J Pathol 1996 180:90-94[CrossRef][Medline]
  40. Saltzman AK, Olson TA, Mohanraj D, Carson LF, Ramakrishnan S. Prevention of postoperative adhesions by an antibody to vascular permeability factor/vascular endothelial growth factor in a murine model. Am J Obstet Gynecol 1996 174:1502-1506[CrossRef][Medline]
  41. Connolly DT, Heuvelman DM, Nelson R, Olander JV, Eppley BL, Delfino JJ, Siegel NR, Leimgruber RM, Feder J. Tumor vascular permeability factor stimulates endothelial cell growth and angiogenesis. J Clin Invest 1989 84:1470-1478
  42. Collins PD, Connolly DT, Williams TJ. Characterization of the increase in vascular permeability induced by vascular permeability factor in vivo. Br J Pharmacol 1993 109:195-199[Medline]
  43. Wu HM, Huang Q, Yuan Y, Granger HJ. VEGF induces NO-dependent hyperpermeability in coronary venules. Am J Physiol 1996 271:H2735-H2739[Abstract/Free Full Text]
  44. Spaziani E. Accessory reproductive organs in mammals: control of cell and tissue transport by sex hormones. Pharmacol Rev 1975 27:207-286[Free Full Text]
  45. Davis JS. Hormonal control of plasma and erythrocyte volumes of rat uterus. Am J Physiol 1960 199:841-846[Abstract/Free Full Text]
  46. Cecil HC, Hannum JA, Bitman J. Quantitative characterization of uterine vascular permeability changes with estrogen. Am J Physiol 1966 211:1099-1102[Free Full Text]
  47. Van Buren GA, Yang D, Clark KE. Estrogen-induced uterine vasodilatation is antagonized by L-nitroarginine methyl ester, an inhibitor of nitric oxide synthesis. Am J Obstet Gynecol 1992 167:828-833[Medline]
  48. Rosenfeld CR, Cox BE, Roy T, Magness RR. Nitric oxide contributes to estrogen-induced vasodilation of the ovine uterine circulation. Clin Invest 1996 98:2158-2166
  49. Chaves MC, Ribeiro RA, Rao VSN. Possible involvement of nitric oxide in estrogen-induced uterine edema in the immature rat. Braz J Med Biol Res 1993 26:853-857[Medline]
  50. Heiss JD, Papavassiliou E, Merrill MJ, Nieman L, Knightly JJ, Walbridge S, Edwards NA, Oldfield EH. Mechanism of dexamethasone suppression of brain tumor-associated vascular permeability in rats. Involvement of the glucocorticoid receptor and vascular permeability factor. J Clin Invest 1996 98:1400-1408[Medline]
  51. Finn CA. Cellular changes in the uterus during the establishment of pregnancy in rodents. J Reprod Fertil Suppl 1982 31:105-111[Medline]
  52. Huet YM, Dey SK. Role of early and late oestrogenic effects on implantation in the mouse. J Reprod Fertil 1987 81:453-458[Abstract/Free Full Text]
  53. McClaren A. Early embryo-endometrial relationship. In: Hubinont PO, Leroy F, Robyn C, Leleux P (eds.), Ovo-Implantation. Basel: Karger; 1970: 18–37
  54. Lundkvist O. Morphometric estimation of stromal edema during delayed implantation in the rat. Cell Tissue Res 1979 199:339-348[Medline]
  55. Rabbani ML, Rogers PA. Role of vascular endothelial growth factor in endometrial vascular events before implantation in rats. Reproduction 2001 122:85-90[Abstract]
  56. Ferrara N, Chen H, Davis-Smyth T, Gerber HP, Nguyen TN, Peers D, Chisholm V, Hillan KJ, Schwall RH. Vascular endothelial growth factor is essential for corpus luteum angiogenesis. Nat Med 1998 4:336-340[CrossRef][Medline]
  57. Fraser HM, Dickson SE, Lunn SF, Wulff C, Morris KD, Carroll VA, Bicknell R. Suppression of luteal angiogenesis in the primate after neutralization of vascular endothelial growth factor. Endocrinology 2000 141:995-1000[Abstract/Free Full Text]
  58. Wulff C, Wilson H, Rudge JS, Wiegand SJ, Lunn SF, Fraser HM. Luteal angiogenesis: prevention and intervention by treatment with vascular endothelial growth factor trap (A40). J Clin Endocrinol Metab 2001 86:3377-3386[Abstract/Free Full Text]
  59. Dickson SE, Bicknell R, Fraser HM. Mid-luteal angiogenesis and function in the primate is dependent on vascular endothelial growth factor. J Endocrinol 2001 168:409-416[Abstract]
  60. McCormack JT, Greenwald GS. Progesterone and oestradiol-17beta concentrations in the peripheral plasma during pregnancy in the mouse. J Endocrinol 1974 62:101-107[Abstract/Free Full Text]
  61. Watson J, Anderson FB, Alam M, O'Grady JE, Heald PJ. Plasma hormones and pituitary luteinizing hormone in the rat during the early stages of pregnancy and after post-coital treatment with tamoxifen (ICI 46,474). J Endocrinol 1975 65:7-17[Abstract/Free Full Text]
  62. Finn CA, Martin L. The role of the oestrogen secreted before oestrus in the preparation of the uterus for implantation in the mouse. J Endocrinol 1970 47:431-438
  63. Milligan SR, Cohen PE, Finn CA. The minimum requirements for oestradiol to induce uterine sensitivity for implantation and decidualization in mice. Hum Reprod 1995 10:1501-1506
  64. Sorger T, Soderwall A. The aging uterus and the role of edema in endometrial function. Biol Reprod 1981 24:1135-1144
  65. Pastore GN, Dicola LP, Dollahon NR, Gardner RM. Effect of estriol on the structure and organization of collagen in the lamina propria of the immature rat uterus. Biol Reprod 1992 47:83-91[Abstract]
  66. Pepper MS, Ferrara N, Orci L, Montesano R. Vascular endothelial growth factor (VEGF) induces plasminogen activators and plasminogen activator inhibitor-1 in microvascular endothelial cells. Biochem Biophys Res Commun 1991 181:902-906[CrossRef][Medline]
  67. Unemori EN, Ferrara N, Bauer EA, Amento EP. Vascular endothelial growth factor induces interstitial collagenase expression in human endothelial cells. J Cell Physiol 1992 153:557-562[CrossRef][Medline]
  68. Verheugen C, Pardridge WM, Judd HL, Chaudhuri G. Differential permeability of uterine and liver vascular beds to estrogens and estrogen conjugates. J Clin Endocrinol Metab 1984 59:1128-1132[Abstract]



This article has been cited by other articles:


Home page
 EndocrinologyHome page
G. W. Aberdeen, S. J. Wiegand, T. W. Bonagura Jr., G. J. Pepe, and E. D. Albrecht
Vascular Endothelial Growth Factor Mediates the Estrogen-Induced Breakdown of Tight Junctions between and Increase in Proliferation of Microvessel Endothelial Cells in the Baboon Endometrium
Endocrinology, December 1, 2008; 149(12): 6076 - 6083.
[Abstract] [Full Text] [PDF]

Home page
 Hum Reprod UpdateHome page
S. R. Hansson, B. Bottalico, V. Noskova, and B. Casslen
Monoamine transporters in human endometrium and decidua
Hum. Reprod. Update, November 5, 2008; (2008) dmn048v1.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
H. M. Fraser, H. Wilson, A. Silvestri, K. D. Morris, and S. J. Wiegand
The Role of Vascular Endothelial Growth Factor and Estradiol in the Regulation of Endometrial Angiogenesis and Cell Proliferation in the Marmoset
Endocrinology, September 1, 2008; 149(9): 4413 - 4420.
[Abstract] [Full Text] [PDF]

Home page
 DevelopmentHome page
M. J. Laws, R. N. Taylor, N. Sidell, F. J. DeMayo, J. P. Lydon, D. E. Gutstein, M. K. Bagchi, and I. C. Bagchi
Gap junction communication between uterine stromal cells plays a critical role in pregnancy-associated neovascularization and embryo survival
Development, August 1, 2008; 135(15): 2659 - 2668.
[Abstract] [Full Text] [PDF]

Home page
 Hum Reprod UpdateHome page
S. R. Soares, R. Gomez, C. Simon, J. A. Garcia-Velasco, and A. Pellicer
Targeting the vascular endothelial growth factor system to prevent ovarian hyperstimulation syndrome
Hum. Reprod. Update, April 2, 2008; (2008) dmn008v1.
[Abstract] [Full Text] [PDF]

Home page
 Hum ReprodHome page
C. Alvarez, I. Alonso-Muriel, G. Garcia, J. Crespo, J. Bellver, C. Simon, and A. Pellicer
Implantation is apparently unaffected by the dopamine agonist Cabergoline when administered to prevent ovarian hyperstimulation syndrome in women undergoing assisted reproduction treatment: a pilot study
Hum. Reprod., December 1, 2007; 22(12): 3210 - 3214.
[Abstract] [Full Text] [PDF]

Home page
 ReproductionHome page
J Sengupta, P G L Lalitkumar, A R Najwa, D S Charnock-Jones, A L Evans, A M Sharkey, S K Smith, and D Ghosh
Immunoneutralization of vascular endothelial growth factor inhibits pregnancy establishment in the rhesus monkey (Macaca mulatta)
Reproduction, June 1, 2007; 133(6): 1199 - 1211.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
A. A. Kazi and R. D. Koos
Estrogen-Induced Activation of Hypoxia-Inducible Factor-1{alpha}, Vascular Endothelial Growth Factor Expression, and Edema in the Uterus Are Mediated by the Phosphatidylinositol 3-Kinase/Akt Pathway
Endocrinology, May 1, 2007; 148(5): 2363 - 2374.
[Abstract] [Full Text] [PDF]

Home page
 Biol. Reprod.Home page
A. E. Roberts, L. K. Arbogast, C. I. Friedman, D. E. Cohn, P. T. Kaumaya, and D. R. Danforth
Neutralization of Endogenous Vascular Endothelial Growth Factor Depletes Primordial Follicles in the Mouse Ovary
Biol Reprod, February 1, 2007; 76(2): 218 - 223.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
R. Gomez, M. Gonzalez-Izquierdo, R. C. Zimmermann, E. Novella-Maestre, I. Alonso-Muriel, J. Sanchez-Criado, J. Remohi, C. Simon, and A. Pellicer
Low-Dose Dopamine Agonist Administration Blocks Vascular Endothelial Growth Factor (VEGF)-Mediated Vascular Hyperpermeability without Altering VEGF Receptor 2-Dependent Luteal Angiogenesis in a Rat Ovarian Hyperstimulation Model
Endocrinology, November 1, 2006; 147(11): 5400 - 5411.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
J. E. O'Brien, T. J. Peterson, M. H. Tong, E.-J. Lee, L. E. Pfaff, S. C. Hewitt, K. S. Korach, J. Weiss, and J. L. Jameson
Estrogen-induced Proliferation of Uterine Epithelial Cells Is Independent of Estrogen Receptor {alpha} Binding to Classical Estrogen Response Elements
J. Biol. Chem., September 8, 2006; 281(36): 26683 - 26692.
[Abstract] [Full Text] [PDF]

Home page
 Mol Hum ReprodHome page
V. Noskova, B. Bottalico, H. Olsson, A. Ehinger, R. Pilka, B. Casslen, and S. R. Hansson
Histamine uptake by human endometrial cells expressing the organic cation transporter EMT and the vesicular monoamine transporter-2
Mol. Hum. Reprod., August 1, 2006; 12(8): 483 - 489.
[Abstract] [Full Text] [PDF]

Home page
 Endocr. Rev.Home page
H. N. Jabbour, R. W. Kelly, H. M. Fraser, and H. O. D. Critchley
Endocrine Regulation of Menstruation
Endocr. Rev., February 1, 2006; 27(1): 17 - 46.
[Abstract] [Full Text] [PDF]

Home page
 ReproductionHome page
A. Matsuoka-Sakata, H. Tamura, H. Asada, I. Miwa, T. Taketani, Y. Yamagata, and N. Sugino
Changes in vascular leakage and expression of angiopoietins in the corpus luteum during pregnancy in rats
Reproduction, February 1, 2006; 131(2): 351 - 360.
[Abstract] [Full Text] [PDF]

Home page
 Cancer Res.Home page
A. J. Garton, A. P.A. Crew, M. Franklin, A. R. Cooke, G. M. Wynne, L. Castaldo, J. Kahler, S. L. Winski, A. Franks, E. N. Brown, et al.
OSI-930: A Novel Selective Inhibitor of Kit and Kinase Insert Domain Receptor Tyrosine Kinases with Antitumor Activity in Mouse Xenograft Models
Cancer Res., January 15, 2006; 66(2): 1015 - 1024.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
H. M. Fraser, H. Wilson, K. D. Morris, I. Swanston, and S. J. Wiegand
Vascular Endothelial Growth Factor Trap Suppresses Ovarian Function at All Stages of the Luteal Phase in the Macaque
J. Clin. Endocrinol. Metab., October 1, 2005; 90(10): 5811 - 5818.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Endocrinol.Home page
A. A. Kazi, J. M. Jones, and R. D. Koos
Chromatin Immunoprecipitation Analysis of Gene Expression in the Rat Uterus in Vivo: Estrogen-Induced Recruitment of Both Estrogen Receptor {alpha} and Hypoxia-Inducible Factor 1 to the Vascular Endothelial Growth Factor Promoter
Mol. Endocrinol., August 1, 2005; 19(8): 2006 - 2019.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
G. S. Nakhuda, R. C. Zimmermann, P. Bohlen, F. Liao, M. V. Sauer, and J. Kitajewski
Inhibition of the Vascular Endothelial Cell (VE)-Specific Adhesion Molecule VE-Cadherin Blocks Gonadotropin-Dependent Folliculogenesis and Corpus Luteum Formation and Angiogenesis
Endocrinology, March 1, 2005; 146(3): 1053 - 1059.
[Abstract] [Full Text] [PDF]

Home page